I already have the original STL of a small container and simply need the inner wall modified to accept a metric thread that will let a 7 mm-thick cable screw in smoothly. This is a prototype, so print-ready accuracy matters more than cosmetic perfection. Here is what I’m after: take the file I supply, add a clean, standard metric internal thread sized for an M7 cable (I’m open to your recommendation on pitch—something typical that prints reliably is fine) and keep the rest of the model exactly as-is. Wall thickness, exterior form, and overall dimensions must remain untouched so it still mates with the other parts of my assembly. When you’re done, send back the updated, watertight STL ready for FDM printing; if you work in a native CAD package and can also drop me a STEP of the final version that would be great but not mandatory. Quick turnaround appreciated, as I’d like to test-print this prototype later this week.